Methods of making paper tissue, towel, and the like, are well known, including various features such as Yankee drying, through-air drying (TAD), fabric creping, dry creping, wet creping, and so forth. Conventional wet pressing processes have certain advantages over conventional through-air drying processing including: (1) lower energy costs associated with the mechanical removal of water rather than transpiration drying with hot air, and (2) higher production speeds, which are more readily achieved with processes that utilize wet pressing to form a web. On the other hand, through-air drying processing has been widely adopted for new capital investment, particularly, for the production of soft, bulky, premium quality tissue and towel products.
Fabric creping has been employed in connection with papermaking processes that include mechanisms for compactive dewatering of the paper web as a means to influence product properties. See U.S. Pat. Nos. 4,689,119 and 4,551,199 to Weldon; U.S. Pat. Nos. 4,849,054 and 4,834,838 to Klowack; and No. 6,287,426 to Edwards et al. Operation of fabric creping processes has been hampered by the difficulty of effectively transferring a web of high or intermediate consistency to a dryer. Note also, U.S. Pat. No. 6,350,349 to Hermans et al., which discloses a wet transfer of a web from a rotating transfer surface to a fabric. Further United States Patents related to fabric creping more generally include the following: U.S. Pat. No. 4,834,838; No. 4,482,429, No. 4,448,638, as well as No. 4,440,597 to Wells et al.
In connection with the papermaking processing, fabric molding has also been employed as a means to provide texture and bulk. In this respect, U.S. Pat. No. 6,610,173 to Lindsey et al. discusses a method of imprinting a paper web during a wet pressing event that results in asymmetrical protrusions corresponding to the deflection conduits of a deflection member. The '173 patent reports that a differential velocity transfer during a pressing event serves to improve the molding and imprinting of a web with a deflection member. The tissue webs produced are reported as having particular sets of physical and geometrical properties, such as a pattern densified network and a repeating pattern of protrusions having asymmetrical structures. With respect to wet-molding of a web using textured fabrics, see, also, the following U.S. Pat. Nos. 6,017,417 and 5,672,248 both to Wendt et al.; U.S. Pat. Nos. 5,505,818 and 5,510,002 to Hermans et al. and No. 4,637,859 to Trokhan. With respect to the use of fabrics used to impart texture to a mostly dry sheet, see U.S. Pat. No. 6,585,855 to Drew et al., as well as United States Patent Application Publication No. 2003/0000664, now U.S. Pat. No. 6,607,638.
Through dried, creped products are disclosed in the following patents: U.S. Pat. No. 3,994,771 to Morgan, Jr. et al.; U.S. Pat. No. 4,102,737 to Morton; and U.S. Pat. No. 4,529,480 to Trokhan. The processes described in these patents comprise, very generally, forming a web on a foraminous support, thermally pre-drying the web, applying the web to a Yankee dryer with a nip defined, in part, by an impression fabric, and creping the product from the Yankee dryer. A relatively permeable web is typically required, making it difficult to employ recycle furnish at levels that may be desired. Transfer to the Yankee typically takes place at web consistencies of from about 60% to about 70%. See also, U.S. Pat. No. 6,187,137 to Druecke et al. As to the application of a vacuum while the web is in a fabric, the following are noted: U.S. Pat. No. 5,411,6363 to Hermans et al.; U.S. Pat. No. 5,492,598 to Hermans et al.; U.S. Pat. No. 5,505,819 to Hermans et al.; U.S. Pat. No. 5,510,001 to Hermans et al.; and U.S. Pat. No. 5,510,002 to Hermans et al.
U.S. Pat. No. 5,851,353 to Fiscus et al. teaches a method for can drying wet webs for tissue products, wherein a partially dewatered wet web is restrained between a pair of molding fabrics. The restrained wet web is processed over a plurality of can dryers, for example, from a consistency of about 40 percent to a consistency of at least about 70 percent. The sheet molding fabrics protect the web from direct contact with the can dryers and impart an impression on the web. See also U.S. Pat. No. 5,336,373 to Scattolino et al.
Despite numerous advances, through-dry processes tend to be expensive in terms of fixed costs and operating expense and remain relatively intolerant of recycle fiber. On the other hand, wet-pressed products tend to have lower absorbency and bulk.
In accordance with the present invention, the absorbency, bulk and stretch are improved by can drying, for example, prior to high solids fabric creping in a pressure nip and, thereafter, final drying the web. The process of the invention has the high speed and furnish tolerance to recycle fiber of conventional wet press processes, and is practiced without transferring a partially dried web to a Yankee dryer. A still further advantage of the invention is that the process can be practiced on existing flat paper machine assets modified to make premium tissue and towel basesheet.